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Bitops/fast-rotate

Fast-rotate

fast-rotate-left is logically identical to rotate-left and fast-rotate-right is logically identical to rotate-right.

fast-rotate-left and fast-rotate-right are actually macros. Generally, they expand into a call of rotate-left and rotate-right respectively. But in the common cases where n is explicitly 8, 16, 32, or 64, they instead expand into a call of a specialized, inlined function.

Macro: fast-rotate-left

(defmacro fast-rotate-left (x width places)
  (cond ((eql width 8)
         (cons 'rotate-left-8
               (cons x (cons places 'nil))))
        ((eql width 9)
         (cons 'rotate-left-9
               (cons x (cons places 'nil))))
        ((eql width 16)
         (cons 'rotate-left-16
               (cons x (cons places 'nil))))
        ((eql width 17)
         (cons 'rotate-left-17
               (cons x (cons places 'nil))))
        ((eql width 32)
         (cons 'rotate-left-32
               (cons x (cons places 'nil))))
        ((eql width 33)
         (cons 'rotate-left-33
               (cons x (cons places 'nil))))
        ((eql width 64)
         (cons 'rotate-left-64
               (cons x (cons places 'nil))))
        ((eql width 65)
         (cons 'rotate-left-65
               (cons x (cons places 'nil))))
        (t (cons 'rotate-left
                 (cons x (cons width (cons places 'nil)))))))

Macro: fast-rotate-right

(defmacro fast-rotate-right (x width places)
  (cond ((eql width 8)
         (cons 'rotate-right-8
               (cons x (cons places 'nil))))
        ((eql width 9)
         (cons 'rotate-right-9
               (cons x (cons places 'nil))))
        ((eql width 16)
         (cons 'rotate-right-16
               (cons x (cons places 'nil))))
        ((eql width 17)
         (cons 'rotate-right-17
               (cons x (cons places 'nil))))
        ((eql width 32)
         (cons 'rotate-right-32
               (cons x (cons places 'nil))))
        ((eql width 33)
         (cons 'rotate-right-33
               (cons x (cons places 'nil))))
        ((eql width 64)
         (cons 'rotate-right-64
               (cons x (cons places 'nil))))
        ((eql width 65)
         (cons 'rotate-right-65
               (cons x (cons places 'nil))))
        (t (cons 'rotate-right
                 (cons x (cons width (cons places 'nil)))))))

Subtopics

Rotate-left-9
Rotate-left-8
Rotate-left-65
Rotate-left-64
Rotate-left-33
Rotate-left-32
Rotate-left-17
Rotate-left-16
Rotate-right-65
Rotate-right-64
Rotate-right-33
Rotate-right-32
Rotate-right-17
Rotate-right-16
Rotate-right-9
Rotate-right-8